1. Field of the Invention
This invention relates to a medical tube assembly. More particularly, it relates to a tube assembly provided with a breakaway plug which is very unlikely to be contaminated during connection with another member.
2. Description of Related Art
Referring to FIG. 5b, there is illustrated one prior art tube assembly. A Y-shaped branch tube 30 illustrated in FIG. 5b comprises a main tube 31 and a branch tube 32. The main tube 31 has two openings, that is, a proximal opening 31a to be connected to a venipuncture needle (not shown) for blood collection, and a distal opening 31b to be connected to a tubing 33b which is further connected to a blood bag (not shown). The branch tube 32 has a distal opening 32b which has a blood-returning assembly mounted thereon.
The component constituting the blood-returning assembly are shown together with the branch tube 30 in FIG. 5a in an exploded state. The blood returning assembly comprises a sleeve 34 mounted on the distal opening 32b, connector 35 fitted in the sleeve 34, caulking member 36 to fluid-tightly join the sleeve 34 and the connector 35, and a rubber cap 37 fitted on the connector 35. The blood returning assembly is enclosed in an envelope 38 for preventing contamination. The envelope 38 has a peeling line 39 for ease of opening the envelope 38.
Upon returning blood corpuscles, the envelope 38 is opened at the peeling line 39, and the cap 37 is then removed for connecting another member to the connector 35.
The blood returning assembly as described above has a plurality of drawbacks as described below.
(1) Since the blood returning assembly comprises a number of components, the number of joints are also increased resulting in an increased risk of contamination. Efficiency in course of assembly is also lowered.
(2) Since the medical solution in the blood bag directly contacts the rubber cap via tubings, amount of the substances eluted from the rubber cap is increased although the amount is below the standard value.
(3) The rubber cap may be loosened, or even come off in an extreme case, due to an increased inner pressure of the blood bag during an autoclave sterilization of the system.
(4) The blood returning assembly is wrapped with the envelope by way of precaution against the contamination in (3). Upon returning the blood corpuscles, a troublesome step of opening the envelope is required before taking the rubber cap off. Complicated operation increases the risk of contamination and lowers the operation efficiency.